Creative Developments (Cosmetics) Limited

Natural Ingredients: SPC 2001

John Woodruff

Natural ingredients almost invariably mean materials from botanical sources although minerals may also be regarded as natural. The formulating chemist believes that those involved in marketing cosmetics assume that all substances grow naturally and that the chemist uses synthetic alternatives for an easier life. When they ask for natural cosmetic products marketing cannot understand why a long debate on the meaning of natural then ensues. The end result is a compromise and obviously some products are more natural than others. A study of folk medicine repeatedly shows that the same plants are used by different cultures to alleviate similar problems and investigations into the constituents of those plants has yielded some very interesting materials.

This feature is going to look at some of the active ingredients derived from natural sources of interest for cosmetic products.

The active principal in many extracts are a group of aromatic compounds collectively called flavonoids. Approximately 5,000 flavonoids have been reported and because they have a common biosynthetic origin, they each have the 2-phenyl-chroman linkage as the same basic structural element. They can be grouped according to the degree of oxidation of the central pyran ring and a distinction is drawn between anthocyans; 2-phenylchromones - the flavones and flavonols; 3-phenylchromans – the isoflavones and isoflavanones; 2-phenylchromans – the flavans, flavan-3-ols, flavan-3,4-diols, chalcones, dihydrochalcones and aurones. An important class of flavonoids are the polyphenols, which contain at least one diphenol aromatic ring and the phenol groups may be optionally etherified or esterified.

Flavonoids are frequently coloured; the chalcones and aurones are yellow and anthocyanosides may be red, blue or violet. Flavonoids are responsible for the coloration of the flowers, the fruits and sometimes the leaves and because they absorb UV radiation, they protect plant tissues against its harmful effects. Many flavonoids have antioxidant properties; others inhibit enzyme reactions. The isoflavones, genistein and daidzein, are phyto-estrogens, which are much weaker than steroid estrogens, but they do have significant interactions with the organism and may reduce the effects of ageing, including the improvement of the quality of skin and the delay of osteoporosis.

Flavonoids with interesting medicinal and cosmetic applications were described by Hans Brand [1] at In-Cosmetics 2001. According to Brand, skin ageing is usually related to lipid per-oxidation and oxidative stress. The efficacy of flavonoids as anti-oxidants is related to their ability to quench oxygen-based free radicals, which occur as a result of UV radiation. Cosmetic products incorporate vitamin C and/or vitamin E to counteract this free radical activity but topical application of flavonoids such as quercetin and rutin has been shown to be at least 20 times more active than vitamin C and 50 times more effective than vitamin E. It was also found that the efficacy of vitamin C was enhanced when used in combination with these flavonoids.

Extract of Camellia sinensis or green tea is popular as both a dietary supplement and a cosmetic ingredient. It is a powerful antioxidant but to be effective the active principals need to be separated from the plant. A patent granted to Indena [2] describes a solvent extraction and evaporation procedure. Approximately 1 kg of Camellia sinensis leaves yield about 100 g solids of which approximately 10% are polyphenols comprising 50-65% epigallocatechin-3-O-gallate, 13-20% epicatechin-3-O-gallate, 2-4% epicatechin and 1.5-3% epigallocatechin. A patent granted to L’Oreal [3] describes the extraction of Ginko biloba leaves with a non-polar solvent; the extract is evaporated to dryness and mixed with polyphenols extracted from Camellia sinensis or from Rosmarinus officinalis, which yields carnosic acid and carnosol, or from Quercus infectoria, which yields substantial quantities of tannic acid. It is claimed that a combination of ginkgo extract and polyphenol may be used to prevent or treat cell damage caused by free radicals induced by atmospheric pollutants and ultraviolet radiation to the skin, scalp or mucous membranes.

A patent granted to P&G [4] describes compositions containing the flavonoids chalcone, flavanone, isoflavone, coumarin, flavone, chromone, dicoumarol, chromanol or mixtures thereof in anti-aging creams. They are particularly effective when used with retinol or with alpha hydroxy acids but the applicants stress that, as with other anti-aging products, their effect only lasts as long as the product is regularly applied. Although the pure flavonoids are named the effect could be reproduced using extracts rich in the flavonoids named. However it should be remembered that the flavonoid content of botanical extracts is affected by their instability due to the presence of free phenolic groups, which oxidize readily on contact with oxygen or light and that many commercially available extracts have lost all activity. It is possible to stabilise the material by forming an ester and this has the advantage of ensuring stability and rendering the material lipo-soluble without affecting its antioxidant or anti-enzyme properties [5]. It is claimed that the esterases present in the epidermis are capable of cleaving the ester group, thus releasing the original flavonoid and the organic acid used to form the ester.

Using a synthesised chemical that is identical to one found naturally in plants and then stabilising it by esterification brings us back to the natural debate between chemists and marketing departments; is the material still natural?

Turning to commercially available materials of natural origin with substantiated claims Sederma has recently launched Heliogenol, a concentrated extract of Helianthus annuus (sunflower) seeds in butylene glycol. Incorporation at from 0.20 – 1.0% in shampoos, conditioners and hair rinses is said to protect the hair against UV-induced damage and free radical activity. Regular application is recommended to prolong natural and artificial hair colouring. Sederma supplies natural extracts with the active agents present to a standardised strength. Newly introduced is Melaslow, an extract of Citrus unshui, Japanese mandarin, in glycerin. The active ingredient is tyramine, which inhibits tyrosinase activity and melanin production, making it suitable for skin whitening products and the treatment of age spots.

Although the majority of plant-derived active ingredients are water-soluble some are to be found as oils and extraction of these requires different techniques. A paper [6] presented at In-Cosmetics described extraction of active ingredients from natural materials using hypercritical CO₂ extraction. Hypercritical fluids exhibit a pressure and temperature-dependent dissolving power and by adjusting these parameters extraction, fractionation and purification processes can be designed. The author described the extraction of the active ingredients from Serona repens fruit and Curcurbita pepo seeds. Biochemical studies indicate that they exert an anti-androgenic activity through the inhibition of reductive, the enzyme which catalyses the transformation of testosterone in the more active dihydrotestosterone (DHT). Sebum is continuously secreted from the sebaceous gland, and its excessive production can lead to skin disorders such as oily skin, seborrhoea, seborrhoeic dermatitis, and acne. Androgens and estrogens regulate sebum production and enzymes and receptors involved with DHT have been found in sebaceous glands. The authors found an improvement in sebum regulation with a decrease in greasiness and associated problems when the extracts were topically applied to human volunteers in a suitable emulsion. A hypercritical CO₂ extract of Zanthoxylum bungeanum was used to treat itchy skin (pruritus) with significant success, although it is the first time that I have seen itches categorised by degrees of noisiness!

Oatmeal is an ingredient with a long history of use for skin treatment but until recently its properties have been accepted on an empirical basis. In 1978 the FDA approved the use of colloidal oatmeal as a Category 1 skin protectant and it appears in the German Pharmacopoeia as an infusion for the relief of skin itchiness. A paper presented at the IFSCC Congress 2000 [7] described an investigation into the anti-irritant properties of oatmeal. Despite the outer kernel of the oatmeal being rich in phenol compounds the authors found that an extract of the whole grain was more effective. A combination of selective chromatographic techniques together with specifically designed HPLC steps disclosed five main fractions of the oat kernel extract:

q Prolamine proteins

q UV-adsorbing non-polar fraction (avenacins, alkyl ferulates)

q Flavonoids

q Avenanthramides

q Saponins (Avenacins, Avenacosides)

The five different fractions were evaluated for their ability to reduce UV-induced skin erythema in humans and analysis of the data revealed that nearly all the anti-irritant potential of the oat extract originates from the avenanthramides. These are phenolic amides formed from differently substituted aminophenolic acids with cinnamic acid and its derivatives and this information has now been utilised by Dragoco to produce standardised oat extracts for cosmetics with scientific and clinical data to support product claims.

Soy protein represents an appropriate raw material of natural origin for commercial production of phytosterols, which are said to improve skin tone of exposed solar radiation subjects and to reduce pruritus, sunburn and peeling. Soybean protein aqueous extract is a proteinase inhibitor. The elastase inhibition of leukocytes and elastase fibroblasts prevent irritation and skin inflammation caused by excessive exposure to the sun, chemical products and environmental factors. Soybean protein is also rich in amino acids and Cognis Care Chemicals supply hydrolysed soy protein as Gluadin Soy, to be used for hair protection and strengthening products. Supporting literature shows the hydrolysate to be substantive to hair and to penetrate the cuticle, particularly at sites of hair damage. It is claimed to adhere to the shaft as a protective film, improving hair strength and gloss and to also increase hair volume. Another protein hydrolysate with similar properties is Hydrosolanum from Croda Oleochemicals. Literature from the supplier show the results of hair penetration and protection studies and the increase in skin and hair moisture content when Hydrosolanum is applied at 1% in a suitable base. Also from Croda is Ryzasol, a rice protein hydrolysate that is added at 1% to skin care products for improved moisturising. It is a film-forming compound and has a pronounced skin tightening effect, making it suitable for eye creams and for smoothing the appearance of fine lines and wrinkles. Crodarom, the French subsidiary of Croda Oleochemicals, specialises in botanical extracts including a special range from organically grown or wild flowers. Its latest catalogue of Phytexcell extracts lists the INCI name, the main active ingredients to be found in the extract, its properties and cosmetic applications. The catalogue also shows the common name in English, French, German and Spanish, the parts used, if it has been organically grown and whether it has Japanese approval. For those interested in organically grown natural materials ICSC of Denmark supply a number of natural oils and butters.

Quest International is well known as a perfume supplier to the cosmetics industry and it also produces a number of specialised extracts including some from vegetables and spices. Among the latter is Capsicum annum (paprika), a dark orange liquid with warming properties that is also a counter-irritant and anti-oxidant and that is suitable for toothpastes and oral care. Piper nigrum or black pepper oil is a clear pale yellow liquid with antiseptic and vascular dilation properties and Ellettaria cardamon seed extract is a concentrated aqueous extract with a historical claim to aphrodisiac properties. Other extracts from Quest include Cassia karintji, Eugenia caryophyllus or clove flower, Myristica fragens (nutmeg) and Cymbopogon flexuosus or lemongrass. Many of these extracts are used in ayurevedic medicine and have been concentrated to maximise their activity.

For those interested in Ayurevedic and Unani medicine I can highly recommend http://www.unaniherbalist.com/ The introduction to this web site states “The Himalayas have given us a wealth of plant life, in the form of herbs, fruits & flowers with incredible properties, yielding to us some of the most precious ingredients, with powerful healing & rejuvenating qualities. Their virtues have been extolled in our ancient Vedic texts and they have become a part of the Indian herbal tradition of Unani and Ayureveda” The site lists many plants with their Latin, English, Sanskrit, Arabian and Persian names and the majority are beautifully illustrated.

1. Brand H, Dansik P, Brand-Garnys E, Flavonoids: Looking In The Face Of Cosmeceuticals. In-Cosmetics, Düsseldorf 2001.

2. USP 6,096,359, Indena, August 2000.

3. USP 5,686,082, L’Oreal 1997

4. USP 6,093,411, The Procter & Gamble Company, July 2000

5. USP 6,235,294, Coletica, May 2001

6. Cristoni A, Arguillère K, Berry N, Girard P, Cosmetic Applications of Hypercritical CO₂ Plant Extracts, In-Cosmetics

7. Vollhardt J, Fielder D A, Redmond M J, Identification and Cosmetic Application of Powerful Anti-Irritant Constituents of Oat Grain; IFSCC International Congress 2000, Berlin